Can a skin test be wrong?

TwinMama83

I'm asking because we had our first visit with the allergist on Monday and the skin test came back positive for a few things, and negative for a few things.  One of the things it was negative for was peanuts, so I gave my kids their first PB&J yesterday and they were just fine.  It was also negative for shellfish. But then as I'm staring at the shrimp I was going to fix for dinner I thought, "What if the skin test was wrong?"  I didn't think to ask the allergist if a negative skin test meant that they could actually have that food, but I will at our next appointment. 

I'm just wondering if any of you have gotten a negative result on the skin test, and then a positive reaction from that food or in a blood test?

ABColeslaw

Not only can it be wrong, at this age it is often wrong.  That is why all our testing is blood testing and biopsy testing.  I'm not messing around with inaccurate testing. 

mrs_kelly1014

Yep, they can absolutely be wrong which is why most allergists will test both blood and do a scratch test to collect more information. The younger the kid, the more likely they are to be inaccurate as well - I think my allergist said up until 2 years old is when they have the most false results. After 2 years old, they can start to trust the scratch tests a bit more.

TwinMama83

Thanks ladies.  I will treat the skin test that we did as "preliminary" and won't offer any more of those allergenic foods until after we have more concrete blood tests.

magdusia

yup! my son was tested negative for soy and as soon as i introduced it to him he had a reaction.  Nothing severe -just bad rash.

Either way -i wouldn't give shell fish to an 11 month old. 

macchiatto

Definitely. Will tested negative on the skin test for corn, wheat and strawberries, yet he clearly reacted to those any time he ate even small amounts of them.

He also tested positive for both eggs and peanuts. With peanuts he also tested positive on the RAST test, but it was a false positive for eggs.